Use of alternative adjuvant systems to produce neutralizing IgY antibodies against Bothrops alternatus venom

LEIVA C.; CANGELOSI, A.; MARICONDA V.; CELI A.; GEOGHEGAN, PATRICIA; BRERO ML; FERNANDEZ MIYAKAWA, M.; CHACANA P.

Buenos Aires

Congreso; 20th World Congress of the International Society on Toxinology; 2019

The use of adjuvant is a key point in the production of antivenoms and currently immunization schemes mostly consider Freund adjuvant. Anyhow, there are other adjuvants that may have a better performance, particularly when the antivenoms are produced on other platforms different from horses, such as egg yolk antibodies (IgY). When choosing an immunomodulator, also tissue damage in the site of injection or economical costs should be considered. The aim of this study was to evaluate the performance of a commercial Montanide? adjuvant to produce an IgY-based antivenom against Bothrops alternatus. Groups of laying hens (n=2) were immunized via i.m. with increasing doses of the venom (40, 80, 120 μg) at days 0, 14 and 28. Hens from Group I received the venom in saline solution (all injections); hens from Group II received venom emulsified only with Montanide? (all injections); and Group III were immunized with the venom emulsified with the adjuvant added with inactivated Salmonella (1st injection) or only the adjuvant (boosters). Serum samples were taken 7 days after each immunization and egg o-based antivenoms were obtained by ammonium sulphate precipitation. To evaluate the seroconversion levels in each Group, titers against the venom were analyzed by ELISA. Median effective dose (ED50) of the antivenoms was assessed in mice according to WHO guidelines. Increasing level of antibodies were observed in the hens from Group III after subsequent immunizations, while no seroconversion was observed in hens from Groups I or II. Regarding the potency of the antivenom obtained from hens of Group III, 1 ml IgY antivenom was able to neutralize 500 μg of the venom. In conclusion, Montanide? commercial adjuvant could be used to produce IgY based-antivenoms against B. alternatus but an immune-stimulant component such as inactivated Salmonella is needed to elicit the response.